Detection and analysis of target objects in medical images are useful and important tasks. For example, detection and diagnosis of abnormal anatomical regions in radiographs, such as masses and microcalcifications in women's breast radiographs (mammograms), are among the most important and difficult tasks performed by radiologists.
Breast cancer is a leading cause of premature death in women over forty years old. Evidence shows that early detection, diagnosis and treatment of breast cancer significantly improves the chances of survival, reducing breast cancer morbidity and mortality. Many methods for early detection of breast cancer have been studied and tested, among them mammography. To date, mammography has proven to be the most cost effective means of providing useful information to diagnosticians regarding abnormal features in the breast and potential risks of developing breast cancer in large populations. The American Cancer Society currently recommends the use of periodic mammography and screening of asymptomatic women over the age of forty with annual examinations after the age of fifty. Mammograms may eventually constitute one of the highest volume X-ray images routinely interpreted by radiologists.
An ongoing tension is found in today's radiology environment between providing high-quality image review and maintaining adequate patient throughput to keep costs under control. Despite ongoing advances in imaging technology and related data processing systems, it is the radiologist who continues to bear the burden of the cost-quality tradeoff. As used herein, radiologist generically refers to a medical professional that analyzes medical images and makes clinical determinations therefrom, it being understood that such person might be titled differently, or might have differing qualifications, depending on the country or locality of their particular medical environment.
Even subtle user interface issues associated with image presentation tools and/or decision support tools can have a significant impact on the radiologist review rate and/or the quality of detection/diagnosis. One issue relates to user analysis of a particular point or region of interest in a particular mammography view. Because of the nature of mammography being a projection of a partially compressed three-dimensional object, the human breast, into a two dimensional image plane, in some situations the radiologist may find it difficult to distinguish a mass or microcalcification from an overlap of tissues aligned along the axis of projection of the image. To make the distinction, the radiologist may examine a second view of the same breast, in an effort to determine the location in the second image that corresponds to the region of interest in the first image. The radiologist will make a visual comparison, sometimes aided by a separate ruler or simply using the radiologist's hand or fingers, of the radial distance of suspicious regions from the nipple. If these radii are roughly the same, it may lead to the conclusion that the region of interest is indeed a mass or microcalcification. If, on the other hand, there is no distinct mass or microcalcification in the second image at the appropriate location, it may lead to a conclusion that the region of interest in the first image is not a mass or microcalcification. In such cases it might be caused by, for example, an overlap in tissues along the axis of projection. In an example in the situation of screening mammography, a region of interest (ROI) may be identified in a craniocaudal (“CC”) view, and radiologist would then like to view a corresponding region in a mediolateral oblique (“MLO”) view.
Some techniques have been proposed and/or used that relate or attempt to relate ROI's between different views for other purposes. For example, U.S. Pat. No. 6,553,356 proposes detecting abnormal regions in living tissue by obtaining images from different views. In particular, the CAD system would make use of the distance from a ROI to the nipple as a basis for establishing identity of ROI's in another view of the same breast for the purpose of improving the CAD system's accuracy. U.S. Pat. No. 6,630,937 is an example of a known onscreen graphical annotation and measurement tool. In particular, tools such as an onscreen measurement ruler and a measuring square are proposed. U.S. 2005/0096530 A1 proposes an apparatus and method for customized report viewing of breast images such as MRI. The apparatus aims to alleviate problems associated with dealing with many hundreds of MRI images. The disclosure discusses one or more volumes of interest being displayed in multiple medical images and accompanied by measurements such as distance from the volume of interest to the nipple.
However, the above proposals do not appear to address solutions for shortcomings that are at least partially addressed by one or more of the preferred embodiments herein. For example, in the situation where a point or region of interest is already identified in first medical image and is not yet identified in second medical image, none of the above proposals appear to facilitate a user to determine the location or locations in the second image that correspond to the point or region of interest in the first medical image by highlighting potential locations in the second image.